Volume of an irregular space

Chazz Michael Michaels

Hi, I am planning/designing my garden, and I'm trying the calculate how many litres of fertiliser I'm going to need.

The green space to the left is the one I'm trying to calculate, the depth being 0.2m. And assume the top length to be 0.8m.

How do I do this? Too long since the LC...

5uspect

You could simply count the number of green pixels, once you know the spatial size of a pixel. Another way is to split each irregular bit into rectangles and triangles and sum the area of each bit.

Once you have the area, multiply by the height to get the volume.

MathsManiac

There must be some error in your measurements. Down the left hand side, the measurements 1.5, 0.9 and 1.2 add up to less than 4.54, but should clearly add up to more than 4.54.

Anyway, divide the area into rectangles and triangles on your sketch. Measure the sides of the rectangles and triangles in the garden and record them on your sketch; (this will include making some diagonal measurements).

The area of a rectangle is length x width. To find the area of a triangle of sides a, b, and c, first work out the value of s = (a+b+c)/2, and then use the formula:
Area = square root of [s x (s-a) x (s-b) x (s-c)].

As 5uspect said, once you have the area, you can multiply by the depth to get the volume.

If you don't really need to be that accurate, you could just estimate the average width of the irregular portions, and work it out as rectangle(s).

im invisible

very roughly, take it as an area of 4.5 X 2 meters, = 9 square metres, X .2 = 1.8 cubic m, = 1800 litres,

but you are hardly going to use that much peat moss, to a depth of 20 cm (8 inches)??

to the gardening forum

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Chazz Michael Michaels

im invisible wrote: »

very roughly, take it as an area of 4.5 X 2 meters, = 9 square metres, X .2 = 1.8 cubic m, = 1800 litres,

but you are hardly going to use that much peat moss, to a depth of 20 cm (8 inches)??

to the gardening forum

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Hmm, I dunno. That 4.54 should be 3.54, I think. So, 1400? I have do look into it more...

Kenny Logins

If you use Sketchup (free) to draw up the plans it will automatically calculate and display volume in the 'entity' window.

http://www.sketchup.com/intl/en/

Chazz Michael Michaels

Kenny Logins wrote: »

If you use Sketchup (free) to draw up the plans it will automatically calculate and display volume in the 'entity' window.

http://www.sketchup.com/intl/en/

Perfect. Thanks!